1. Field of the Invention
The present invention relates to an ophthalmologic apparatus, for example, an eye fundus camera, used in ophthalmology hospitals or the like.
2. Related Background Art
As an example of an ophthalmologic apparatus, there is an apparatus in which stereophotography for an eye fundus of an eye of a person (patient) to be examined can be performed. Generally, the stereophotography has a method of obtaining right and left stereo images simultaneously by photo taking one time and a method of obtaining right and left stereo images by photo taking two times with states where a commonly used photo taking apparatus is shifted to right and left positions. Also, there is a method of obtaining right and left stereo images by changing an angle of parallel flat surface plates disposed between a main mirror and an eye (Japanese Patent Application Laid-Open No. 8-196509). However, the above methods have the following points for improvement.
First, in a simultaneous stereophotography method, since two independent optical systems are required for photo taking of right and left images, the apparatus has a complicated structure and is expensive. Further, since photo taking of the right and left images is performed simultaneously for a pupil limited in size, separation between illumination light and photo taking light is hard, and it is difficult to obtain a wide view angle and a sufficient base length simultaneously.
Second, in a method of obtaining right and left stereo images by photo taking two times with states where a commonly used photo taking apparatus is shifted to right and left positions, a photo taking time is increased. Also, since an interval of time for photo taking of the right and left stereo images is long and a change, for example, rotation occurs in an eye fundus during this interval, it is difficult to obtain precise stereo images.
Third, in a method of performing stereophotography by changing an angle of parallel flat surface plates disposed between a main mirror and an eye, since the moveable flat surface plate is disposed right in front of the main mirror, the limitation on a physical arrangement is large, so that an operation distance of a lens is shortened and operationality during photo taking is deteriorated. Photo taking quality is deteriorated and occurrences of a ghost and a flare are caused due to aberration by the flat surface plate.
Conventionally, in an ophthalmologic apparatus, for example, in an eye fundus camera for photo-taking an eye fundus of a person to be examined, alignment between the pupil and an optical system at photo taking is commonly performed by an operator manually. An apparatus, which is obtained by improving the above apparatus, for performing automatic alignment by actuating an entire optical system in up, down, right and left directions or in an optical axis direction is known (Japanese Patent Application Laid-Open No. 11-146864). However, the above apparatus has the following points for improvement.
First, since in an ophthalmologic apparatus such as an eye fundus camera the number of adjustment or determination items, such as a position relationship between the pupil and the optical system, an operation distance in an optical axis direction, focusing of the eye fundus and a photo taking range of the eye fundus, is large, adjustment operation by hand cannot be performed easily.
Second, in an apparatus for performing automatic alignment by actuating an entire optical system, it is difficult to actuate the optical system with large weight rapidly. Thus, rapid tracking of the optical system to movement of the eye can not be performed easily. This causes the size of the apparatus to be large and the cost to be high.
Main object of the present invention is to improve a conventional ophthalmologic apparatus. One concrete object is to provide an excellent ophthalmologic apparatus in which stereo eye fundus images of the eye can be obtained suitably. One further concrete object is to provide an ophthalmologic apparatus in which stereophotography can be performed with extremely high precision, regardless of a structure in which the number of movable portions is small and which is simple and has high reliability, that is, an ophthalmologic apparatus in which both high reliability and high precision can be attained with high grade.
To attain the above object, according to one aspect of the present invention, there is provided an ophthalmologic apparatus comprising a diaphragm, a photo taking system, having a mirror system with a deflection mirror, for taking an eye fundus image through the mirror which is disposed in a position nearer to an eye to be examined than to the diaphragm in an optical path, and a controller for controlling the photo taking system so as to perform photo taking plural times by changing directions of the mirror, thereby obtaining a plurality of images for the eye fundus from a plurality of directions.
Another object of the present invention is to provide an excellent ophthalmologic apparatus in which eye fundus images of the eye can be obtained suitably. A further concrete object is to provide an ophthalmologic apparatus in which photo taking can be performed with extremely high precision by alignment with high speed and high precision, regardless of a structure in which the number of movable portions is small and which is simple and has high reliability, that is, an ophthalmologic apparatus in which both high reliability and high precision can be attained with high grade.
To attain the above object, according to another aspect of the present invention, there is provided an ophthalmologic apparatus comprising a diaphragm, a photo taking system, having a mirror system with a deflection mirror, for taking an eye fundus image through the mirror which is disposed in a position nearer to an eye to be examined than to the diaphragm in an optical path, and a light source for leading light to the eye fundus of the eye through the mirrors to illuminate the eye fundus.
Further objects of the present invention and embodiments thereof are clear in explanation of the embodiments below.